The present invention relates to a device for the determination of the quantitative composition of gases.
A device of this type for the determination of the composition of gases which uses the method of gas extraction from samples of insulating oil at reduced pressure to obtain the quantities of gas necessary for an analysis is already known from the publication "Betriesuberwachung durch Untersuchungen des Isolierols" ("Plant monitoring by means of examinations of the insulating oil") by Dornenburg and Hutzel (Elektrotechn. Z. A, vol. 98, 1977, pages 211 to 215).
In the device of the publication, before the actual sample of insulating oil is drawn off, a sufficient quantity of pre-rinse oil is extracted to ensure that the sample of insulating oil originates from the interior of the container of the electrical apparatus and not from supply lines and stopcocks. To avoid gas losses and adulteration due to external air foreign to the sample, the insulating oil sample is expediently drawn off in an evacuated sample container with air excluded. This sample container is then transported to a fixed laboratory, often over considerable distances.
In the laboratory the insulating oil is transferred from the sample container to a larger evacuated vessel, during which process gases dissolved in the insulating oil are liberated. These liberated gases are continuously pumped into a gas collecting vessel by means of a Toepler pump until the insulating oil is fully degassed. These gases are then analysed in a gas chromatograph.
In the above described process it proves to be disadvantageous that there are large distances between the point at which the insulating oil sample is removed and the fixed laboratory so that considerable waiting times must be expected before the analysis results are available. A portable gas detector is also known which permits the proportion of combustible gases in the gas cushion of an electrical apparatus filled with insulating oil to be determined. It is, however, not possible to determine the quantitative proportion of each gas component with this gas detector. In addition, it can be used only for apparatus having a gas cushion.